<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .active {
            text-decoration: underline;
        }

        .text-dangr {
            font-weight: bold;
        }
    </style>
</head>

<body>
    <script src="../js/vue.js"></script>
    <div id="app">
        <div v-bind:class="[isActive ? 'active':'','text-danger']">Hello School!</div>
    </div>
    
    <script>
        let vm = new Vue({
            el: "#app",
            data: {
                isActive: true
            }
        })
    </script>
</body>

</html>